Electromagnetic motor



Much 9, 1943.

J. A. TRAYLOR EIAL ELECTROMAGNETIC MOTOR Filed Aug. 6. 1941 1 zum zzfoza I7 19 202 el 51"z 5 33 8 rFh 7 5l 4 p 42 47 4.5 i i "5 1 m' 46 .m'

BY TTOP.

Patented Mar. 9, 1943 ELECTROMAGNETIO MOTOR John A. Traylor, deceased,late of Denver, Colo., by Tessie S. Traylor, Edna T. Eisenhaud, and JohnB. Traylor, executors, Denver, Colo., and John B. Traylor, Denver, Colo.

Application August 6, 1941, Serial No. 405,724

7 Claims.

Our invention relates to an electromagnetic motor and has particularreference to an electromagnetic reciprocating tool finding particularutility when employed as a rock drill or like percussion tool.

Many attempts have been made prior to our invention to construct acompact and eflicient reciprocating electromagnetic motor, but ltheseattempts have not been entirely successful in that the devices wereheavy, operated at low efficiency and were incapable of delivering largeout-puts of power without destructive overheating.

When one of the prior electromagnetic reciprocating tools was used as apercussion rock drill, difficulty was often encountered in the stickingof the drill in the hole due to the packing of rock dust and chipsbehind the cutting head of the drill. Whenever a drill became stuck inthe hole, the electromagnetic motor was useless as a device for removingthe drill since it would produce only downwardly directed impactsserving only to stick the drillstill tighter.

The present invention is directed to the provision of an electromagneticmotor of the character above discussed and it is an object of ourinvention to provide a motor which overcomes the above noteddisadvantages and which is relatively compact and eiiicient inoperation.

It is also an object of our invention to provide an electromagneticmotor of the reciprocating type employing a plunger which isreciprocated by the alternate energization of opposed electromagnets.

It is a still further object of our invention to provide a motor of thecharacter set forth in the preceding paragraphs in which a centralportion of the plunger is enlarged and tapered to coact with conicalthroat portions of the electromagnets to produce an air gap pull at thethroat in addition to the presently utilized solenoid pull and air gappull at the inner stop.

It is an additional object of our invention to provide a motor of thecharacter set forth in the preceding paragraphs in which a novel form ofelectromagnet winding is employedfto reduce the self-inductance of thecoil to thereby increase the speed of action of the motor and to providefor a higher operating eillciency than has been hitherto possible toreduce the size and weight of the device.

It is alsoan object of our invention to provide an electromagneticreciprocating percussion device capableof producing both upwardly anddownwardly directed impacts upon a percussion tool.

It is additionally an object of our invention to provide a percussiondevice of the character set forth in the preceding paragraph whichincludes a means for adjusting the strength or violence of the upwardlydirected impact at will and without aiecting the strength of thedownwardly directed impacts.

Other objects and advantages of our invention will be apparent from astudy of the following specifications, read in connection with theaccompanying drawing, wherein:

Fig. 1 is a perspective view illustrating the electromagnetic motor ofour invention as embodied in a novel form of percussion tool such as arock drill;

Fig. 2 is an enlarged elevational view of the device shown in Fig. 1with parts broken away and other parts shown in section to illustratethe details of construction;

Fig. 3 is a fragmentary end view of the device taken substantially alongthe line III-III of Fig.2; and

Fig. 4 is a schematic wiring diagram illustrating the electricalconnections employed to operate the device.

Referring to the drawing, We have illustrated in Fig. l anelectromagnetic percussion device as including a pair of opposed magnetstructures I and 2 adapted to eiect a reciprocation o'f a longitudinallymovable plunger 3 to thereby create work producing impacts on apercussion actuated tool such as a rock drill 4.

Each of the stationary electromagnet struc- 'tures I and 2 is preferablyconstructed as illustrated in detail in Fig. 2 and includes asubstantially cylindrical shell portion 5 of a suitable magneticmaterial carrying longitudinally extending radial fins 6 employedprincipally for the purpose or assisting in the dissipation of heatgenerated within the device. A selected group of the fins 6 are providedwith circumferentially extending feet I which may be interengaged .bysuitable fastening means such as rivets or screw threaded bolts 8 tosecure the magnet structures I and 2 to eacn other and hold thesestructures in the desired spaced relation and in axial alignment witheach other.

The magnet shell 5 is preferably internally bored as indicated at 9 toprovide a cylindrical recess within which an electromagnet coil l0 isreceived. The coil I0 is preferably wound upon a spool consisting of aninner cylindrical spool shank I I formed of a suitable non-magneticmaterial and carrying spool end flanges I2 and I3 formed of a suitableinsulating material such as fiber, Bakelite, or similar substance.

In winding the magnet II, .there is preferably first Wound an innermostlayer I4 of insulating material such as glass tape, mica-paper orasbestos tape (a preference being expressed for those insulatingmaterials capable of withstanding relatively high temperatures). Uponthe spool shank I I there is then wound a plurality of independentcoaxial multi-layer solenoid coils I5, each of the coils I 5 beinginsulated from adjacent coils as by means of interposed layers I5 of aheat-resistant insulating material.

Exteriorly of the spool ends I2 and I3 we position inner and outerterminal rings I1 and Il suitably insulated from the coil III and fromthe magnet structure 5 as by means of insulating material I9. Liketerminals of each of the coils I5 are connected as by conductors 2i! tothe ring I1, for example, and the opposite like terminals of the coilsare connected as by means of conductors 2| to the ring I8. 'I'hus therings I1 and I8 comprise in-put and output terminals, respectively, forall of the individual coils I5, which coils are connected in parallelbetween such input and out-put terminals.

By employing a plurality of solenoid coils I5 mounted coaxially withrespect to each other and connected in parallel in the manner abovedescribed, we have been able to provide a solenoid capable of producinga relatively large magnetomotive force which is characterized by havinga relatively low self-inductance. It is important to keep theself-inductance of the coil as low as possible since the speed of actionof the electromagnetic motor is limited primarily by the selfinductanceof the coil. Furthermore, coils having, a high self-inductance causeburning and rapid destruction of the contacts which are employed toenergize and de-energize the coils.

After the coil is assembled, it is preferably impregnated with cement orother impregnating material having the property of withstandingrelatively high temperatures and having reasonably high heatconductivity. One such impregnating material which we have found to beeminently satisfactory consists of a mixture of extremely ne sand andLuminite cement with water, which mixture after impregnation sets toform a hard, solid and mechanically strong onepiece structure. Luminiteis a special Portland type cement manufactured by the Atlas CementCompany and characterized particularly by having an extremely lowshrinkage and rapid setting characteristic.

The coil structure thus formed is retained within the cylindrical recess9 as by means of a cover plate 22 which is secured to the magnet shell 5as by means of bolts 23 threadedly engaged in tapped holes provided inboss-like portions 24 formed integrally with a selected plurality of theVentilating fins 6.

The interior bore of the spool shank II serves as a guiding bore forreceiving a cylindrical portion 25 of the plunger 3. The end of thecylindrical portion 25 is preferably provided with a conical or taperedform indicated at 26 to coact with a similarly tapered cone-shapedrecess 21 formed in the innermost end of a fixed stop member 28 formedby preference integrally with the end cap member 22. Upon energizationof the solenoid coil I0, the plunger is drawn upwardly to bring theconical end 26 into engagement with the conical recess 21.

Magnetic sticking of the plunger to the stop member 23 may be avoided bylining the conical recess 21 with a thin layer 28 of non-magneticmaterial such as manganese steel or other suitable alloy having therequisite strength and 5 hardness. Cushioning of the plunger orresistance to upward movement of the plunger resulting from air beingtrapped in the conical recess 21 may be avoided by providing a breatheropening 30 extending into communication with the exterior of the magnetstructure.

'I'he lower portion of the magnet shell l is preferably formed ofconsiderable thickness and provided with a tapered throat portion orentrance aperture 3| which is adapted to coact with a similarly taperedportion 32 of the plunger 3. The plunger 3 is enlarged at its centralportion as indicated at 33 to provide a pair of the tapered conicalportions 32 Awhich extend in opposite directions from the enlargement32.

The lower end of the plunger 3 is preferably identical in form and shapeto the upper end which is illustrated in Fig. 2 and the lower magnetstructure 2 is preferably identical in construction with the magnetstructure I above described with the exception that the lower 'magnetstructure 2 is provided with a movable lower stop member 34. Thismember, like the stop member 28, is provided. with a conical recessadapted to coact with the conical lower end of the plunger but insteadof being formed integrally with the lower end cap is mounted for axialsliding movement relative thereto as by being extended through asuitable aperture II formed in the end cap 35.

The stop member 34 may be shouldered as indicated at 31 to provide aseat adapted to coact with the end cap 35 in confining a compressionspring 38 between the shoulder 31 and the end cap. The stop member 34may include a bleeder 40 port 39 which may, by means of transverselyextending bores 40, be extended into communication with the annularspace within which the compression spring 33 is received. 'Ihe outermostend of the stop member 38 may be bored and threaded as indicated at 4Ior otherwise arranged to carry a chuck member 42 within which the shankportion 43 of the rock drill 4 is received. i i i i In the form shown inFig. 2, the chuck member 42 is provided with a tapered bore 44 and theshank portion 43 of the drill 4 is similarly tapered, whereby engagementof the two tapered surfaces provides the necessary detachable engagementof the rock drill with the chuck member. The shank of the drill 4 ispreferably provided with an annular enlargement 45 positioned behind aU-shaped clip member 45 (see Figs. 2 and 3) which is in turn carried bya pair of forwardly extending arms 41 pivotally secured as indicated at4I in bosses 43 formed on the exterior surface of the end cap 35.

It will be observed that whenever a downward pressure is exerted on themagnet structures I and 2 as by means of handles 50 when the rock drill4 is engaged with the piece to be drilled, the movable stop member 34will be urged upwardly relative to the stationary magnet structures Iand 2 until a shoulder 5I formed on the chuck 42 engages the under sideof the cap member 35. This serves also to position the enlargement 45 aconsiderable distance upwardly from the U-shaped yoke 46. If theelectromagnets retained within the magnet structures I and 2 arethereupon alternately energized and de-energized, the plunger 3 will bereciprocated in synchronism with such alternation and will, upon eachdownward stroke, strike the upper end of the movable stop member 34 anddeliver an impact thereto which, by virtue of the connection afforded inthe chuck member 44, will be transmitted to the drill 4 to cause thedrill to perform the desired work.

In case the drill becomes stuck in the hole, the tool may be used toexert outwardly directed impacts on the drill for the purpose ofassisting in the removal of the stuck drill. This is accomplished bymerely exerting an upwardly directed vforce on the handles 50, whereuponthe yoke member 46 is moved upwardly until it engages the enlargement 45of the drill shank. Alternate energization and de-energization of themagnet structures and 2 thereupon produces a reciprocation of theplunger 3 which, upon striking the upper stop member 23, will deliver animpact to the stationary magnet structures I and 2 tending to move suchstructures forwardly in the direction of the force which is exertedthereon. These upwardly directed impacts are transmitted directly to thedrill 4 through the arms 41 and the yoke 46 and by this means removal ofthe stuck drill is greatly facilitated.

We have illustrated in Fig. 4` the electrical connections which may beemployed to control the operation of the electromagnetic motor abovedescribed. In Fig. 4 a suitable source of direct current is illustratedas comprising a direct current generator 52, one terminal of which isconnected as by means of a conductor 53 through a control switch 54 tointerconnected ends of the upper magnet coil |01 and the lower magnetcoil |02. The other terminal of the generator 52 is connected as bymeans of a conductor 55 to the movable member 56 of a commutatingswitch. The movable member iS adapted to be driven by a suitable drivemeans 51 which may comprise a clockwork or an electric motor energizedfrom a suitable source of power.

In its rotation the member 56 is adapted to make alternate contact witha plurality of contact points 58 and 59. The contact points 58 are allconnected in 'parallel and are connected to the free end of the coil |02as by means of a conductor 60 and similarly the contact points 59 areall connected in parallel and are connected as by means of a conductor6l to the free end of the magnet coil |01. Thus, as the arm 56 rotates,the magnet coil |02 is rst energized and then de-energized and then themagnet coil |01 is energized and subsequently de-energized so as toproduce the above described reciprocation of the plunger 3.

We have found it desirable to provide a means for regulating theviolence or intensity of the blow which is struck by the plunger 3 whenit is moved to its uppermost position and for this purpose we interposein the conductor 6| a tapped resistance 62, the various taps of whichare extended into connection with a selector switch 63, the movable armportion 64 thereof being connected to the conductor 6|. Thus, theselector switch 63 may be employed to insert all of the resistance 62 incircuit with the coil |01 or to progressively cut out portions of theresistance 62 until all of the resistance is cut out to apply fullvoltage to the coil |01. It is intended that the switches 63 and 54 bemounted in a suitable manner upon the magnet structure l so as to beconveniently available for manipulation by an operator using the tool.

At this point attention is particularly directed to the enlarged centralportion 33 of the plunger 3, the coned sections 32 adjacent thereto, andthe similarlyl coned throat portion 3| which is provided on each of themagnet structures and 2. By employing this form of construction we havebeen able to obtain a greater tractive force upon the plunger 8 from agiven number of ampere turns in the electromagnet coils II than hashitherto been possible.

The pull which is exerted by the magnet coill I0 on the plunger 3comprises, in the form of construction above described, threecomponents:

namely- (1) The solenoid effect tending to pull the cylindrical portion25 into the magnetic center of the coil |0, l

I(2) 'I'he air gap pull at the upper stop 2l tending to pull the conicalend 26 into engagement with the conical recess 21, and

-(3) An air gap pull at the throat 3| tending to pull the coned collarportion 32 into engagement with the coned throat 3|.

By forming the surfaces 3I-32 and 26--21 as cones rather than asradially extending plane surfaces, a much longer stroke is permissiblewithout producing an excessive air gap between the plunger and thecomponent parts of the magnetic circuit formed by the stop member 28,the shell 5 and the throat portion 3 I.

From the foregoing it will be observed that we have'provided a novelform of reciprocating electromagnetic motor which is characterizedparticularly by employing a novel magnet construction resulting in a lowself-inductance ofthe solenoid employed and permitting the solenoid tobe operated with higher eiliciency than has been hitherto possible.Furthermore, the use of the cement or similar hardening, impregnatingmaterial hereinbefore described permits the solenoid coils tosuccessfully withstand the shocks and jars resulting from the operationof the device.

The magnet structures are further characterized by the employment of theconed central collar portion of the plunger which provides for a muchgreater tractive effort from a magnet of a given magnetomotive forcethan has hitherto been realized.

It will also be observed from the foregoing that we have illustrated anddescribed a, novel form of percussion tool adapted to produce bothinwardly and outwardly directed impacts upon a rock drill or similartool and that means has been provided for regulating the force of theupwardly directed impacts to permit these impacts to be used at will forthe purpose of removing drills which have become stuck in the drillholes.

While we have shown and described the preferred embodiment of ourinvention,'we do not desire to be limited to any of the details ofconstruction shown or described herein, except as defined in theappended claims.

We claim:

1. In an electromagnetic reciprocating motor, the combination of: a pairof opposed electromagnet structures having aligned plunger receivingbores; a plunger reciprocal in said bores, said plunger including endportions received in said bores and a central enlargement, saidenlargement defining opposed conical surfaces; and a magnet housing foreach of said electromagnet structure, said housings having theirinwardly facing ends formed with a conical throat portion contoured toconiorm to and'closely receive the conical portions of said centralenlargement.

2. In an electromagnetic reciprocating motor, the combination of: aplunger comprising a cylindrical member having a central enlargementdefining opposed conical portions disposed with their bases adjacenteach other; a pair of multiturn solenoids one for each end of saidplunger, each having a plunger receiving bore therein; and a magnetcasing for each of said solenoids, each of said casings including acylindrical portion surrounding said solenoid, an outer end cap deningan outer stop for arresting movement of said plunger into said solenoid,and an inner end member having a plunger receiving aperture 'formedtherein in alignment with said plunger receiving bore, said aperturebeing of conical form deiining a tapered surface conforming to andclosely receiving said conical portion of said plunger when said plungeris moved into said solenoid.

3. In an electromagnetic reciprocating motor, the combination of: a pairof encased opposed electromagnet structures, each of said structuresincluding a plurality of longitudinally extending radial heatdissipating fins, at least a part of said fins on each of saidstructures being extended to a point substantially midway between saidstructures and terminating in transversely extending feet; and meanssecuring the feet carried by one structure to the feet carried by theother structure to thereby secure said structures to each other and holdthe same in a predetermined axial spaced relation to each other.

4. In an electromagnetic percussion device, the combination of:interconnected upper and lower electromagnet structures; means foralternately energizing said structures; a plunger reciprocal betweensaid structures in response to said alternate energization; a movablestop carried by said lower structure in a position to receive downwardlydirected impacts from said plunger; means on said movable stop forholding a percussion tool and transmitting said impacts thereto; anupper stop fixed on said upper electromagnet structure in a position toreceive upwardly directed impacts from said plunger; and means carriedby said lower structure for engaging said tool and transmitting saidupwardly directed impacts thereto.

5. In an electromagnetic percussion device, the combination of:interconnected upper and lower electromagnet structures; means foralternately energizng said structures; a plunger reciprocal between saidstructures in response to said alternate energization; a movable stopcarried by said lower structure in a position to receive downwardlydirected impacts from said plunger; means on said movable stop forholding a percussion tool and transmitting said impacts thereto; an 5upper stop fixed on said upper' electromagnet structure in a position toreceive upwardly directed impacts from said plunger; and means on saidlower structure normally disengaged from said tool and engageabletherewith in response to upward movement of said interconnectedstructures relative to said tool for transmitting said upwardly directedimpacts to said tool.

6. In an electromagnetic percussion device, the combination of:interconnected upper and lower l5 electromagnet structures; means foralternately energizing said structures; a plunger reciprocal betweensaid structures in response to said alternate energizatlon; a movablestop carried by said lower structure in a position to receive downwardlydirected impacts from said plunger;

means on said movable stop for holding a percussion tool andtransmitting said impacts thereto; an upper stop iixed on said upperelectromagnet structure in a position to receive upwardly directedimpacts from said plunger; means carirled by said lower structure forengaging said tool and transmitting said upwardly directed impactsthereto; and means for adjusting the strength oi said upwardly directedimpacts independently 'of the strength of said downwardly directedimpcts.

7. In an electromagnetic percussion device, the combination ofinterconnected upper and lower electromagnet structures; means foralternately energizing said structures; a plunger reciprocal betweensaid structures in response to said alternate energization; a movablestop carried by said lower structure in a position to receive downwardb'directed impacts from said plunger;

40 means on said movable stop for holding a percussion tool andtransmitting said impacts thereto; an upper stop fixed on said upperelectromagnet structure in a position to receive upwardly' directedimpacts from said plunger; means carried by said lower structure forengaging said tool and transmitting s aid upwardly directed impactsthereto; and means for adjusting the electrical potential applied tosaid upper structure upon energization thereof to adjust the strengthoi' said upwardly directed impacts.

. TESSIE S. 'I'RAYLOR,

EDNA T. EISENHAND, JOHN B. TRAYLoR,

Co-Executofs of the Estate of John A. TrayZOr,

5s Deceased.

JOHN B. TRAYLOR.

